HTTP Response 401 Authentication Failed

when i “print $result;” I am getting this error… “HTTP Response 401 Authentication Failed”

<?php ini_set('include_path', '.:/usr/lib/php:/usr/local/lib/php:/home/shersoft/php'); require_once('SOAP/Client.php'); $DirectFlight_Authentication = array( 'user' => '***concealed username***', 'pass' => '***concealed activation key***', ); $wsdl_url = 'http://flightaware.com/commercial/flightxml/data/wsdl1.xml'; $WSDL = new SOAP_WSDL($wsdl_url,$DirectFlight_Authentication); $soap = $WSDL->getProxy(); $result = $soap->Enroute('KIAH',10,'airline',0); **print $result;** print "Aircraft en route to KSMO: "; $flights = $result->enroute; foreach ($flights as $flight) { print $flight->ident . " (" . $flight->aircrafttype . ") " . $flight->originName . " (" . $flight->origin . ") "; } ?>

HTTP Response 401 Authentication FailedAircraft en route to KSMO:
Warning: Invalid argument supplied for foreach() in /home/shersoft/public_html/testflightapi.php on line 23

You need a FlightXML key for the password.